/*!
    \file  systick.h
    \brief the header file of systick
    
    \version 2017-06-28, V1.0.0, demo for GD32F3x0
    \version 2019-06-01, V2.0.0, demo for GD32F3x0
*/

/*
    Copyright (c) 2019, GigaDevice Semiconductor Inc.

    Redistribution and use in source and binary forms, with or without modification, 
are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this 
       list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice, 
       this list of conditions and the following disclaimer in the documentation 
       and/or other materials provided with the distribution.
    3. Neither the name of the copyright holder nor the names of its contributors 
       may be used to endorse or promote products derived from this software without 
       specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
OF SUCH DAMAGE.
*/

#ifndef SYS_TICK_H
#define SYS_TICK_H

#include "gd32f3x0.h"
#include <stdint.h>

/* configure systick */
void systick_config(void);


/**
*	@brief	精准延时函数(这里的DS18B20线程得设置为最高)
*	@param	us 延时的us数
*	@retval 无
*/
static __inline void SysTick_Delay_Us(uint32_t us)    //结构体指针
{
    uint32_t i=0;
    //这里先配置SysTick定时器
    SysTick_Config(SystemCoreClock/1000000UL);   //这里其实只是负责1.选择时钟源 2.开中断 3.使能计数器

    for(; i<us; ++i) //定时时长为us微妙
    {
        //当计数器的值减少到0时，CRTL的位16会置1
        while(!((SysTick->CTRL) & (0x01<<16)));   //时间未到，停在这里
        //时间到了之后，将COUNTFLAG位置1,并发生重装，然后会将COUNTFLAG位清零
    }
    //定时完成,关闭
    SysTick->CTRL &=(~SysTick_CTRL_ENABLE_Msk);
}

//另外的一种更简洁的定时编程(延时毫妙)
static __inline void SysTick_Delay_Ms(uint32_t ms)    //结构体指针
{
    uint32_t i=0;
    //这里先配置SysTick定时器
    SysTick_Config(SystemCoreClock/1000UL);   //这里其实只是负责1.选择时钟源 2.开中断 3.使能计数器

    for(; i<ms; ++i) //定时时长为us微妙
    {
        //当计数器的值减少到0时，CRTL的位16会置1
        while(!((SysTick->CTRL) & (0x01<<16)));   //时间未到，停在这里
    }
    //定时完成,关闭
    SysTick->CTRL &=(~SysTick_CTRL_ENABLE_Msk);
}

#endif /* SYS_TICK_H */
